You and I, Let's Part on Good Terms

Sheng Xunfeng has a past no one knows about, and Ning Su, who has been by his side for three years, knows nothing of it. She thinks she is nothing more than a way for him to pass the time when he is bored. Once he grows tired of her, she decides they should part ways and move on. She leaves without looking back, but from then on, he loses his mind over her.